I recently had an excellent experience with DuctMedic for cleaning my dryer vent. My appointment was for 0800 and right around 0745 the crew called and said they were on their way and would be arriving on time.
Once at my house they put booties over their shoes when coming inside, something I very much appreciated. I can't say whether their cleaning is any more thorough than another company so I will say I chose them because they adhere to the standards of the National Air Duct Cleaners Association (NADCA) and state that their personnel "go through a rigorous three-phase, 10-month in-house training process resulting in national certification." (quote taken from their website)
While it is certainly possible for a technician to not be trained on NADCA standards and do a thorough job, knowing they adhere to those standards gives me peace of mind because whether those standards are applicable to dryer vent cleaning or not I know the company trains their people to meet a certain level of performance.
I can say they were on time, courteous, friendly, walked me through the process so I would know they did a thorough job, vacuumed my dryer lint trap, used a bristle brush inside the lint trap to dislodge any stuck-on lint, vacuumed after using the brush, vacuumed the area around my dryer and showed my that part of my issue was a metal mesh over my vent had clogged and I should just go out every few months and clean it. (The mesh is there, I'm guessing, to keep animals from nesting in the vent. We're in a rental, so I haven't dealt with the dryer vent until now.)
I would definitely recommend them.